My favourite bacteria

For a long time after I got back into swimming, I’d be sitting in my office and think that I could smell a turkey roasting. 9am in my (mostly) deserted building, and I would smell turkey. How did we just get from swimming to turkey? Well, it dawned on me that the smell of the pool lingered on my arms. And the smell of a heavily-trafficked pool is the smell of chlorine, or Javex, as I think of it. The smell of chlorine and roasting turkey are strongly linked in my sensory memory.

Gratuitous shot of Christmas dinner

It seems the deep recesses of my brain had combined the smell of Keira’s nanny cooking Christmas turkey with the harsh chemical she would use to clean the sink and every other surface that the raw bird might have touched. Keira’s nanny is the model of cleanliness in food preparation. I keep a clean, though cluttered, kitchen. But I have learned to embrace all sorts of bacteria. And my favourite bacteria are those that grow in yogurt.

I have been making yogurt with skim milk at least once a week, for nearly five years. I learned how to do it from my officemate, who once casually mentioned that she had made yogurt the previous evening. I was taken aback by her description of the method – it sounded like a recipe for food poisoning. I didn’t know then about those lovely little yogurt bacteria that take over the warm milk, turning it into something even healthier than milk alone. I know yogurt is healthy, but I eat it because I like it. It’s tart and creamy, and finds its way into so much of what I cook and bake.

These two old jars are the perfect size for one week's worth of yogurt

I assumed that using skim milk meant my yogurt would have to be thin. I was confused, though, because sometimes my yogurt would be quite runny and other times it would set up as thick as Greek-style yogurt. I tried adding milk powder or straining it once it had set. But after a few years, I stumbled on this post by the Hungry Tigress. She mentioned that holding the yogurt at 175F/80C would create a thicker set. I have done that every time now with flawless results.

The finished yogurt can wobble on a spoon

I’ve also struggled with incubation times and temperatures. In the summer, it’s no problem – it sets well on my kitchen counter. In the winter, though, we keep the place as cool as we can. I bought a yogurt “maker,” which is just an incubator. It worked, but I found it made the yogurt extra bitter (not in a good way), so I started improvising. My fool-proof winter method is to wrap the jars in a towel and oven mitts, place them in a metal tray, and set them by the heating vent. During the day, the yogurt sets in about 6 hours. Alternatively, I can also leave it over night (when the house is even colder) and awake to perfect yogurt.

My DIY yogurt incubator

Everyone seems to be getting into yogurt-making lately. Here is my take on the totally easy, totally worthwhile process.

Plain Jane Yogurt
Milk, any quantity and level of fat (no additives)
A few tablespoons of plain yogurt (no additives) [Note: you only need this for the first batch]
A thermometer – I use a candy thermometer that hooks onto the side of my pot. Any thermometer designed for testing food temperatures should do.

my "candy" thermometer only ever gets used for yogurt

Heat a quantity of your preferred milk to 180F/82C in an appropriately-sized pot. Heat it slowly, stirring every couple of minutes to prevent scorching. Turn off the burner when it hits 180F/82C and leave it for 10 minutes. This will allow it to stay at 175F/80C for a few minutes, ensuring a thick set. Then remove it from the burner and let it cool to 110-115F/43-46C (this usually takes mine about 30 minutes).

In the bottom of clean jars that are large enough to hold your quantity of milk, place about a tablespoon or so of yogurt. Pour in the warm milk and stir it for a second. Tighten the lids on your jars and wrap them in a towel or two. Place the jars in a warm-ish spot.

Check the yogurt after about 4 hours. How’s the set? Still liquidy? Check back in a couple of hours. Already set? Stick them in the fridge.

Next time you make yogurt, just reserve a few tablespoons from your previous batch to start the new one.

This entry was posted in diy, milk, Recipes, yoghurt, yogurt. Bookmark the permalink.

2 Responses to My favourite bacteria

  1. Pingback: My science of pancakes | First Feasts

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